The Highlands are surrounded by water with the Atlantic Ocean on the east, the Cabot Strait to the north and east, the Gulf of St. Lawrence on the north and west, and Bras d'Or Lake to the south. Elevations average 350 metres at the edges of the plateau (i.e. at the above-mentioned water bodies), and rise to more than 500 metres at the centre, including the highest elevation point in the province at White Hill.

The plateau consists of numerous broad, gently rolling hills bisected with deep valleys and steep-walled river canyons. The southern and western edges of the plateau give way to broad valleys with soils resulting from glaciation, providing some of Cape Breton's best agricultural lands. Most of the interior and southern edges of the plateau are covered with damp, cool deciduous forests which makes for spectacular colours during autumn foliage. Southward facing slopes above 300 metres in elevation generally only support Balsam Fir, as a result of the short growing season and harsh winter climate. The northern and western edges of the plateau, particularly at high elevations, resemble arctic tundra.

The west coast of the Highlands meets the Gulf of St. Lawrence in steep cliffs whereas the east coast borders the Atlantic Ocean with a gently sloping coastal plain, low headlands, and several beaches.

In 1936 the federal government established the Cape Breton Highlands National Park covering 950 km² across the northern third of the Highlands. The Cabot Trail scenic highway also encircles the coastal perimeter of the plateau. While the coastal areas of Inverness and Victoria counties along the plateau are home to several dozen small fishing and tourism-related communities, the interior of the plateau has no public roads and very little human presence, making it one of Nova Scotia's largest wilderness areas.